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1. Field of the Invention
The invention relates to apparatus for mounting electrical junction blocks and the like and, more particularly, to an arrangement for mounting such devices in confined areas such as electrical raceways.
2. Description of Related Art
Modem office arrangements often employ removable wall panels or the like to define work areas. Such panels and other structures often have a raceway area for accommodating electrical wiring and electrical junction blocks near the floor or in other locations which do not provide easy access to technicians. Typically, junction blocks are mounted within such raceway areas by attaching them to support brackets. Since the electrical wiring requirements and locations of the junction blocks, some of which may include outlet boxes and the like, depend on the ever-changing needs of the users, junction blocks are often installed or removed after the wall panel structures are in place. Installing or removing a junction block positioned, for example, near the bottom of a wall panel and essentially at floor level, is often an arduous task. Furthermore, the only convenient access to a wall panel may be from only one side. Therefore, it is desirable that junction blocks are easily insertable and removable, and that they are insertable and removable from either side of the wall panel.
U.S. Pat. No. 4,993,576, issued Feb. 19, 1991 to the inventor of the present invention, shows a junction block provided with a latching mechanism comprising a pair of opposing interlocking members hingedly attached to a junction block and arranged to define a channel between opposing edges for engaging a retainer tab. A similar device is disclosed in U.S. Pat. No. 5,051,203 issued May 14, 1991 to Furrow. Junction blocks are typically constructed by adjoining two complementary, separately molded, half sections. The latching arrangement typically has one of the engaging sections molded as an integral part of one half section and the opposing part molded as an integral part of the other half section. The prior art latches comprise opposing and interlocking tongues and grooves. Unless special precautions are taken in the manufacture of these parts, the opposing sections may not be properly aligned, resulting in improper operation of the latch arrangements. A further disadvantage of such prior art arrangements is that a grooved section defined between the opposing edges tends to be reduced in size when the interlocking members are depressed, potentially causing a binding of the tab retained between the opposing edges of the interlocking members.
U.S. Pat. No. 5,259,787, issued Nov. 9, 1993 to the inventor of the present invention, and which is incorporated by reference herein, shows a junction block latching mechanism comprising a latch arm constructed as a cantilever beam. The cantilever beam extends from an outer wall of the junction block and is provided with a transversely extending channel for engagement with a retaining tab attached to a structural member designed to receive the junction block. A shortcoming of a latching mechanism employing such a cantilever beam construction is that it may be difficult to insert the junction block from one side of the frame due to the fact that the free end of the cantilever beam latch is raised to a position such that its ends abut against the tab, thereby preventing an easy installation.
These and other problems of the prior art are overcome in accordance with this invention by a latch member comprising a first cantilever beam and a second retention beam, the second retention beam being of a length differing from the first cantilever beam. The beams are attached to opposing sides of a junction block housing. The first cantilever beam is attached at a first hinge adjacent one side of the housing and extends to a position beyond the centerline of the housing. The second retention beam is attached adjacent an opposite side of the housing and extends from the opposite side to a position overlapping a portion of the upper surface of the first beam. The first cantilever beam is provided with a tab channel aligned with the centerline of the housing, for receiving a retainer tab or the like. An arm section of the first cantilever beam extends between the first hinge and the tab channel of the first cantilever beam, and a further arm section extends away from the first hinge and beyond the tab channel. The two arm sections of the first cantilever beam have sloping exterior surfaces, sloping upwardly toward the tab channel. The sloping surfaces cause the first cantilever beam to be flexed toward the upper wall of the junction block when the junction block is inserted in a raceway area in contact with a retainer tab or the like.
The second retention beam extends from an opposite side of the upper surface of the junction block and extends over a portion of the upper surface of the first cantilever beam toward the tab channel of the first cantilever beam, and is preferably terminated at or before the tab channel. Advantageously, when the junction block is inserted in a frame or the like from the side of the block adjacent the second retention beam, the second retention beam engages the retainer tab or the like and is positioned to exert a force on the free end of the first cantilever arm. In this manner, the second retention beam provides for proper engagement of the first cantilever arm with the retainer tab or the like. Advantageously, the dual beam latching device in accordance with the present invention eliminates a problem of the prior art in which the free end of a single cantilever beam can extend upwardly a sufficient distance so as to tend to engage a side wall of the retainer tab, thereby preventing proper engagement of the tab channel of the cantilever beam with the retainer tab.
In accordance with the present invention, a junction block may be readily disengaged from the side of the junction block which is opposite to the side at which the hinged section of the first cantilever beam attaches to the junction block. The disengagement can be undertaken by pivotal movement of the first cantilever beam about the first hinge, in a manner so that the retainer tab is disengaged from the tab channel. In the same manner, the junction block may be disengaged from the side of the junction block which corresponds to the side at which the hinged section of the first cantilever beam attaches to the junction block. Furthermore, the latch of the present invention overcomes the problem of prior dual, interlocking cantilever beams in that the alignment of the first cantilever beam and the second retention beam is not critical, thereby avoiding the problems encountered in assembly of junction blocks from complementary half sections.